Field of the Invention
The present invention relates to a method for establishing a radio resource control (RRC) connection for a cell of a terminal in a mobile communication system and a terminal using the same.
Related Art
A universal mobile telecommunications system (UMTS) is a 3rd generation asynchronous mobile communication system that operates in wideband code division multiple access (WCDMA) based on European systems such as global system for mobile communications (GSM0 and general packet radio services (GPRS). Long-term evolution (LTE) of the UMTS has been discussed by 3rd generation partnership project (3GPP) that standardizes the UMTS. 3GPP LTE is a technology for high-speed packet communication. The 3GPP LTE requires cost reduction of a user and a provider, improvement of a service quality, coverage and a system capacity which are extended and improved, flexible use of a frequency band, a simple structure, an open interface, and appropriate power use of a terminal. A lot of schemes have been proposed for the requirements.
The terminal can communicate with a base station after establishing a radio resource control (RRC) connection. When the user turns on a power supply of the terminal at first, the terminal first searches an appropriate cell and thereafter, stays in an RRC idle state (RRC_IDLE) in the corresponding cell. The terminal which stays in the RRC idle state makes the RRC connection with an RRC layer of a network through an RRC connection procedure and is transited to the RRC connection state (RRC_CONNECTED) when the terminal needs to make the RRC connection. There are various cases in which the terminal in the RRC idle state needs to make the RRC connection. For example, when uplink data needs to be transmitted due to a call attempt of the user, and the like or a paging message is received from the network, the terminal needs to make the RRC connection with the RRC layer of the network at the time of transmitting a response message thereto.
Meanwhile, in the terminal, an RRC connection failure may repeatedly occur during the RRC connection procedure with a specific cell. For example, a case may occur, in which a downlink quality is good but an uplink quality is not good in the specific cell due to a geographical environment, an irregular distribution of attenuation factors, and the like. In this case, when the terminal measures a signal transmitted by the specific cell, since a downlink reception signal quality is good, the terminal may intend to the specific cell and announce the selection of the specific cell to the specific cell. However, since the uplink quality is not good, the cell selection may not normally be transferred to the specific cell. As a result, the RRC connection failure which is repeated may occur with respect to the specific cell.
Required are a method and an apparatus which can solve the problem.